Field emission light source, an emerging light source having features of large current density, low power consumption, fast responding, etc, has important application prospects in the field of flat-panel display, X-ray source, microwave amplifier and other vacuum electronics fields. The working principle of field emission source is: in the electric field, metal tip at low potential, carbon nano tube and other electron emitters emit electrons that strike phosphor at high potential to produce visible light.
Traditional field emission light source device which has advantages of low operating voltage, no warm-up delay, being highly integrated, energy saving, being environmentally friendly, quick start, being thin and light, good environmental suitability, etc, is mainly used in the field of lighting and display. And, as a new generation of light source in the field of lighting, field emission light source device is developing rapidly owing to its advantages of mercury-free, low energy consumption, uniform luminescence and adjustable light intensity. Conventional field emission light source device mainly uses phosphor as anode, where electron beams strike phosphor that produces visible light under the excitation of electron beams. Sulfides, oxides or silicate phosphor are commonly used as anode luminous materials.
Oxides or silicate phosphor has relatively low electrical conductivity, and is prone to produce charge accumulation at anode under the strike of electron beams, bringing a decrease of potential difference between the two electrodes and an impact on luminous efficiency of field emission light source device. However, in the anode plate using sulfides phosphor having good electrical conductivity, decomposition of sulfides may occur easily and emit gas, which not only decreases the vacuum degree of field emission light source device but poisons the cathode, and ultimately shortens the life of a field emission device.